Which of the following elements likely make up the largest portion of the mass in an organism?

• A. Phosphorus
• B. Sodium
• C. Magnesium
• D. Fluorine

Answer: (A)

Verified step by step guidance

1. Begin by considering the most abundant elements in biological organisms. Typically, these include carbon, hydrogen, oxygen, and nitrogen, which are not listed in the options.
2. Next, evaluate the role of each element provided in the options within biological systems. Phosphorus is a key component of DNA, RNA, and ATP, and is essential for energy transfer and genetic material structure.
3. Consider the relative abundance and biological importance of each element. Phosphorus is more abundant in organisms compared to sodium, magnesium, and fluorine due to its role in nucleic acids and energy molecules.
4. Understand that sodium is primarily involved in nerve function and fluid balance, magnesium is a cofactor for many enzymes, and fluorine is found in trace amounts, mainly in teeth and bones.
5. Conclude that phosphorus, due to its critical role in cellular structures and energy metabolism, likely makes up the largest portion of the mass in an organism among the given options.